1 /* 2 * 74Hx164 - Generic serial-in/parallel-out 8-bits shift register GPIO driver 3 * 4 * Copyright (C) 2010 Gabor Juhos <juhosg@openwrt.org> 5 * Copyright (C) 2010 Miguel Gaio <miguel.gaio@efixo.com> 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License version 2 as 9 * published by the Free Software Foundation. 10 */ 11 12 #include <linux/init.h> 13 #include <linux/mutex.h> 14 #include <linux/spi/spi.h> 15 #include <linux/spi/74x164.h> 16 #include <linux/gpio.h> 17 #include <linux/slab.h> 18 19 struct gen_74x164_chip { 20 struct spi_device *spi; 21 struct gpio_chip gpio_chip; 22 struct mutex lock; 23 u8 port_config; 24 }; 25 26 static struct gen_74x164_chip *gpio_to_74x164_chip(struct gpio_chip *gc) 27 { 28 return container_of(gc, struct gen_74x164_chip, gpio_chip); 29 } 30 31 static int __gen_74x164_write_config(struct gen_74x164_chip *chip) 32 { 33 return spi_write(chip->spi, 34 &chip->port_config, sizeof(chip->port_config)); 35 } 36 37 static int gen_74x164_get_value(struct gpio_chip *gc, unsigned offset) 38 { 39 struct gen_74x164_chip *chip = gpio_to_74x164_chip(gc); 40 int ret; 41 42 mutex_lock(&chip->lock); 43 ret = (chip->port_config >> offset) & 0x1; 44 mutex_unlock(&chip->lock); 45 46 return ret; 47 } 48 49 static void gen_74x164_set_value(struct gpio_chip *gc, 50 unsigned offset, int val) 51 { 52 struct gen_74x164_chip *chip = gpio_to_74x164_chip(gc); 53 54 mutex_lock(&chip->lock); 55 if (val) 56 chip->port_config |= (1 << offset); 57 else 58 chip->port_config &= ~(1 << offset); 59 60 __gen_74x164_write_config(chip); 61 mutex_unlock(&chip->lock); 62 } 63 64 static int gen_74x164_direction_output(struct gpio_chip *gc, 65 unsigned offset, int val) 66 { 67 gen_74x164_set_value(gc, offset, val); 68 return 0; 69 } 70 71 static int __devinit gen_74x164_probe(struct spi_device *spi) 72 { 73 struct gen_74x164_chip *chip; 74 struct gen_74x164_chip_platform_data *pdata; 75 int ret; 76 77 pdata = spi->dev.platform_data; 78 if (!pdata || !pdata->base) { 79 dev_dbg(&spi->dev, "incorrect or missing platform data\n"); 80 return -EINVAL; 81 } 82 83 /* 84 * bits_per_word cannot be configured in platform data 85 */ 86 spi->bits_per_word = 8; 87 88 ret = spi_setup(spi); 89 if (ret < 0) 90 return ret; 91 92 chip = kzalloc(sizeof(*chip), GFP_KERNEL); 93 if (!chip) 94 return -ENOMEM; 95 96 mutex_init(&chip->lock); 97 98 dev_set_drvdata(&spi->dev, chip); 99 100 chip->spi = spi; 101 102 chip->gpio_chip.label = spi->modalias; 103 chip->gpio_chip.direction_output = gen_74x164_direction_output; 104 chip->gpio_chip.get = gen_74x164_get_value; 105 chip->gpio_chip.set = gen_74x164_set_value; 106 chip->gpio_chip.base = pdata->base; 107 chip->gpio_chip.ngpio = 8; 108 chip->gpio_chip.can_sleep = 1; 109 chip->gpio_chip.dev = &spi->dev; 110 chip->gpio_chip.owner = THIS_MODULE; 111 112 ret = __gen_74x164_write_config(chip); 113 if (ret) { 114 dev_err(&spi->dev, "Failed writing: %d\n", ret); 115 goto exit_destroy; 116 } 117 118 ret = gpiochip_add(&chip->gpio_chip); 119 if (ret) 120 goto exit_destroy; 121 122 return ret; 123 124 exit_destroy: 125 dev_set_drvdata(&spi->dev, NULL); 126 mutex_destroy(&chip->lock); 127 kfree(chip); 128 return ret; 129 } 130 131 static int __devexit gen_74x164_remove(struct spi_device *spi) 132 { 133 struct gen_74x164_chip *chip; 134 int ret; 135 136 chip = dev_get_drvdata(&spi->dev); 137 if (chip == NULL) 138 return -ENODEV; 139 140 dev_set_drvdata(&spi->dev, NULL); 141 142 ret = gpiochip_remove(&chip->gpio_chip); 143 if (!ret) { 144 mutex_destroy(&chip->lock); 145 kfree(chip); 146 } else 147 dev_err(&spi->dev, "Failed to remove the GPIO controller: %d\n", 148 ret); 149 150 return ret; 151 } 152 153 static struct spi_driver gen_74x164_driver = { 154 .driver = { 155 .name = "74x164", 156 .owner = THIS_MODULE, 157 }, 158 .probe = gen_74x164_probe, 159 .remove = __devexit_p(gen_74x164_remove), 160 }; 161 162 static int __init gen_74x164_init(void) 163 { 164 return spi_register_driver(&gen_74x164_driver); 165 } 166 subsys_initcall(gen_74x164_init); 167 168 static void __exit gen_74x164_exit(void) 169 { 170 spi_unregister_driver(&gen_74x164_driver); 171 } 172 module_exit(gen_74x164_exit); 173 174 MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>"); 175 MODULE_AUTHOR("Miguel Gaio <miguel.gaio@efixo.com>"); 176 MODULE_DESCRIPTION("GPIO expander driver for 74X164 8-bits shift register"); 177 MODULE_LICENSE("GPL v2"); 178